1. (Field of the Invention)
This invention relates to a glass-ceramic sintered body used as a substrate for loading an integrated circuit and electronic components parts, a process for its production, and a glass-ceramic substrate.
More specifically, it relates to a glass-ceramic sintered body used for loading an integrated circuit (IC) and electronic component parts thereon which sintered body has a high flexural strength, and an increased adhesion strength of a metallizing portion, a process for its production, and a glass-ceramic substrate of the sintered body.
2. (Description of the Prior Art)
A multilayer circuit substrate obtained by integrally firing a plurality of laminated sheets having a predetermined conductive pattern is available as a circuit substrate used, for example, as a hybrid integrated circuit of an electronic device. This multilayer circuit substrate is required to have (1) a thermal expansion coefficient near the thermal expansion of Si (about 35.times.10.sup.-7 /.degree.C.), (2) a high mechanical strength, (3) a low permittivity, and (4) to be able to be fired at a low temperature of about 800.degree. to 1000.degree. C. Among them, (1) is a property which is required to maintain good continuity to an Si chip even under severe temperature environments. The property (2) is a characteristic required to prevent the destruction of the substrate due to stress applied to the substrate or breaking of the substrate in the step of connecting various electronic components or input or output terminals to the multilayer circuit substrate. The property (3) is necessary to increase the speed of propagating a signal of an electronic circuit provided in the multilayer circuit substrate. The property (4) is necessary for using a metal having a low melting point with a low wiring resistance, such as gold, silver or copper as an internal wiring material.
Japanese Laid-Open Patent Publication No. 321258/1992 discloses a composition for production of a multilayer circuit substrate which satisfies the above-mentioned properties, said composition comprising 50 to 90% weight of SiO.sub.2 --Al.sub.2 O.sub.3 --MgO--ZnO--B.sub.2 O.sub.3 type crystalline glass and 10 to 50% by weight of alumina. The crystalline glass of the composition for making a multilayer substrate contains SiO.sub.2, Al.sub.2 O.sub.3, MgO, ZnO and B.sub.2 O.sub.3 in predetermined proportions so that in the crystalline phase after firing, a cordierite phase (2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2) is mainly formed, or the composition is fired so that the cordierite phase is mainly formed.
The adhesion strength of the metallized portion in the circuit substrate is greatly affected by the extent of the flexural strength of the substrate material. When the adhesion strength of the metallized portion in the glass-ceramic substrate is evaluated, if the metallized portion is sufficiently conjugated with the interface of the porcelain, the porcelain in a portion to which the metallized portion adheres is destructed to show a so-called porcelain peeling. Accordingly, in the glass-ceramic substrate, the metallizing strength increases when the flexural strength of the porcelain is high. However, a conventional substrate has a very low flexural strength of about 20 Kg/mm.sup.2, and a very low metallizing strength of 2 Kg/mm.sup.2 or below.
When the adhesion strength of the metallizing portion becomes low as mentioned above, the metallizing portion tends to peel off easily when a lead wire is connected to an input or output terminal portion or when heat treatment is carried out, for example, at the time of plating. Accordingly, the reliability of the substrate becomes a problem.